Some downhole operations, such as cutting a tubular structure, for example, can be improved by centering a tool within the tubular structure that carries out the operation. Cutters often have a plurality of knives, typically from two to five, that extend radially outwardly (or inwardly depending upon the specific application being cut) to engage the tubular structure being cut. The cutter rotates relative to the tubular structure being cut while the knives extend radially outwardly to thereby engage and cut through the wall of the tubular structure. If the cutter is not centered within the tubular structure the knives can contact and cut through a first portion of the tubular structure sooner than a second portion of the tubular structure that is, for example, diametrically opposite of the first portion. Such a cutting condition can cause excessive vibration, tool damage and an interrupted cut.
Consequently, centralizers are used to center the cutter relative to the tubular structure and thereby provide even engagement of the knives with walls of the tubular structures, which in turn results in a more even cut through the walls with less vibration. Centralizers often employ a plurality of flexible metal springs that engage the inside surface of the tubular structure to center the tool within the tubular structure. Such flexible metal springs however may have inadequate force to center a tool, for example when used in a nonvertically oriented tubular structure resulting in inadequate centering of the tool. Accordingly, there is a need in the art for a centralizer that can center tools regardless of biasing forces acting to urge the tools off center.